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lvalue subs return undef, playing with experimental features, the End of the World, etcby erikharrison (Deacon) |
on May 07, 2002 at 05:06 UTC ( [id://164527]=perlquestion: print w/replies, xml ) | Need Help?? |
erikharrison has asked for the wisdom of the Perl Monks concerning the following question: Some of you may remember that I (like Mr. Cawley) am implementing a programing language in Perl (though mine is just a toy). I finally got down to working on the code to implement variables, and happened upon attributes in the docs. Useing lvalue subs I was able to make a delightfully simple API for handling complex data structures with arrays, scalars, and hashes, alng with namespaces and lexical variables. The only problem is that it doesn't work.
This gives no output. This reduces the problem to the basics. Essentially, the lvalue sub does the hard part (be assigned to) but otherwise returns undef, as if the hash key is autovivifiying . . .which it shouldn't be, unless I'm badly mistaken (which I could be :-). I understand that attributes are an experimental don't-use-this-even-if-your-life-depended-on-it feature (which is maturing nicely in Perl 6) but I'm still curious if anyone can explain it. Cheers, (and thanks)Erik
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